The preferred embodiment concerns a method to remove toner deposits on the surface of a cleaning element which accepts electrically charged toner particles from a carrier surface. The preferred embodiment also concerns a device to remove toner deposits on the surface of a cleaning element.
In electrographic printers or copiers, image development methods are used that ink electrostatic charge images on intermediate carrier surfaces (for example charge images on a photoconductor or a photoconductor belt) across an air gap or in direct contact with triboelectrically charged toner particles that are transferred from the surface and applicator element. After the transfer of the toner particles from the applicator element onto the surface of the intermediate carrier, the surface of the applicator element must be cleaned of the remaining untransferred toner particles by a cleaning element, generally by a cleaning roller. The electrically charged toner particles taken up by the cleaning element (which is charged with a predetermined electrical potential) can consolidate as a result of electrical adhesion forces, heat, friction or pressure and lead to a film formation or to caking on the surface. The surface of the cleaning element can thereby be negatively affected in terms of its cleaning function and make the entire printing process unstable. If the fixed deposits on the surface of the cleaning element detach as clumps or fragments, this can lead to the degradation of the function of the developer station (for example insufficient inking) and even damage to it (for example by scratching the surface).
A device to clean an electrode arrangement that comprises a plurality of electrodes which are arranged around small through holes is known from U.S. Pat. No. 6,398,345 B1. With the aid of a control voltage applied to the electrodes, toner particles are let through the through holes or the through holes are blocked so that toner material can be graphically applied to a substrate material present after the electrode arrangement. Toner particles straying about can deposit on the stationary electrode arrangement and plug the through holes. Therefore, between the printing processes a movably borne cleaning device is moved towards the electrode arrangement that detaches and removes the toner particles without contact. For this the device comprises a suction nozzle whose opening is surrounded by an electrode that is charged with voltage. The toner particles are detached from the electrode arrangement with the aid of the electrical fields generated via the voltage and drawn off by the suction nozzle. After detaching the toner particles, the device is removed again in order to be able to continue the printing process.
A device and a method to clean a surface provided with toner particles is proposed in DE 10 2007 019 311 (previously unpublished) by the same applicant. A cleaning roller charged with electrical potential receives electrically charged toner particles from the substrate surface of an applicator element. The toner particles are resupplied to the mixture made up of toner particles and carrier particles and reused. The disclosure content of the aforementioned Patent Application is herewith incorporated by direct reference into the present Application.
Furthermore, reference is made to the prior art according to the documents DE 10 2004 059 532 A1, U.S. Pat. No. 5,311,258 A and DE 101 52 892 A1.